Porangahau River

The Porangahau River has its headwaters in the coastal hill country in the southwest of Hawke’s Bay and flows 35 km before discharging into the Pacific Ocean near Porangahau township. This is a 6th order river which has a catchment area of 697 square kilometres. The river has a mean annual flow of 2.406 cumecs (Porangahau @ State Highway 52 in the lower catchment).

The catchment has a warm dry climate, low elevation, soft sedimentary geology, and is predominately in pastoral land use, with the township on the river above the estuary, which is a distinctive feature at the coast.

The river has poor to average quality habitat for most of its length with regular stream bank slumping and little riparian cover. The catchment is highly erodible, resulting in the stream bed showing regular deposits of fine sediment. New consents for a sewage treatment plant for Porangahau township should help improve water quality.